A semiconductor device is configured such that a semiconductor element is bonded to a substrate through solder and further this assembly is entirely sealingly covered with resin. The substrate however has a large coefficient of linear expansion, resulting in a problem with peel-off of the sealing resin due to hot/cold cycle environments. As a known technique to prevent such peel-off, therefore, there is coating of polyamide resin or polyimide resin to a substrate. As another technique, Patent Document 1 listed below discloses forming a sprayed coat made of aluminum (Al) or silicon oxides (Al2O3, SiO2) on a substrate. The substrate covered with the sprayed coat is firmly bonded to the sealing resin part. Further, Patent Document 2 discloses that a plurality of recesses are formed in a surface of a substrate by punching process using a punch having a plurality of protrusions so that sealing resin filled in each recess is hooked with the substrate to enhance bonding strength therebetween.